Posts Tagged ‘ice’

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Rahmstorf: Is it OK to call him an “alarmist” now?

May 9, 2012

Some folks never give up.  In the following video Stefan Rahmstorf says…

To me a tipping point in the climate system is like a sweet spot in the climate system, where a small perturbation can have a major, even qualitative effect.  It’s like a small change in temperature moving, for example, the Greenland Ice sheet beyond the point where eventually it will melt down all together…from about 2 degrees global warming there would be a risk of the complete meltdown of the Greenland Ice sheet…I think this two degree limit agreed in Cancun by the politicians may not be enough to prevent a dangerous interference in the climate system.

Now let’s be clear about this: a “complete meltdown” of the Greenland ice sheet would raise the planet’s sea level 7 meters (7000 mm).  The sea level rise rate today is about 3 mm per year and decreasing according to satellite data.  A rational reading the tide gauge data is even less.

I guess in Greenland ice must melt at -25°C.  Here is today’s temperature outlook…

Oh, I know, the scientifically sophomoric sophisticated will tell us all about the rapidly accelerating glaciers.  Well, their favorite journal, Science, throws a little icy cold water on their dreams of catastrophic nirvana.  In 21st-Century Evolution of Greenland Outlet Glacier Velocities ( T. Moon, et. al., Science, 4 May 2012, Vol. 336, pp. 576-578)  Moon et. al. produced “a decade-long (2000 to 2010) record documenting the ongoing velocity evolution of nearly all (200+) of Greenland’s major outlet glaciers.”  They found that in some regions there was a glacier acceleration (SEE! SEE!), but not very consistently over the last 10 years.  Here is their conclusion

Our observations have implications for recent work on sea level rise. Earlier research (33) used a kinematic approach to estimate upper bounds of 0.8 to 2.0 m for 21st-century sea level rise. In Greenland, this work assumed ice-sheet–wide doubling of glacier speeds (low-end scenario) or an order of magnitude increase in speeds (high-end scenario) from 2000 to 2010. Our wide sampling of actual 2000 to 2010 changes shows that glacier acceleration across the ice sheet remains far below these estimates, suggesting that sea level rise associated with Greenland glacier dynamics remains well below the low-end scenario (9.3 cm by 2100) at present. Continued acceleration, however,may cause sea level rise to approach the low-end limit by this century’s end. Our sampling of a large population of glaciers, many of which have sustained considerable thinning and retreat, suggests little potential for the type of widespread extreme (i.e., order of magnitude) acceleration represented in the high-end scenario (46.7 cm by 2100). Our result is consistent with findings from recent numerical flow models (34).

So, Rahmstorf is worried about a “complete meltdown of the Greenland ice sheet” which would lead to 7 meters (7000 mm) of sea level rise, but the data shows “sea level rise associated with Greenland glacier dynamics remains well below the low-end scenario (9.3 cm by 2100)” (93 mm by 2100).  Does being off by a factor of 75 (7000/93) qualify as “alarmist?”

By the way, when Moon says “Earlier research (33) used a kinematic approach to estimate upper bounds of 0.8 to 2.0 m for 21st-century sea level rise” he is talking about Kinematic Constraints on Glacier Contributions to 21st Century Sea-Level Rise (Pfeffer, et. al., Science, 5 September 2008, Vol. 321. no. 5894, pp. 1340 – 1343).  I discussed this paper at length two years ago in my “Reply to John Mashey.” (Still feeling smug, John?) 

And finally,  Moon’s last sentence says “Our result is consistent with findings from recent numerical flow models (34).”  He is talking about Committed sea-level rise for the next century from Greenland ice sheet dynamics during the past decade (Price, et. al., PNAS, 31 May 2011, vol. 108 no. 22 pp. 8978-8983).    Price, et. al. say

The modeling conducted here and some reasonable assumptions can be used to make approximate upper-bound estimates for future SLR from GIS [Greenland Ice Sheet] dynamics, without accounting for future dynamical changes explicitly. As discussed above, numerous observations indicate that the trigger for the majority of dynamic thinning in Greenland during the last decade was episodic in nature, as the result of incursions of relatively warm ocean waters. By assuming that similar perturbations occur at regular intervals over the next century and that the ice sheet responds in a similar manner, we can repeatedly combine (sum) the cumulative SLR [sea level rise] curve from Fig. 4B to arrive at additional estimates for SLR by 2100. For example, if perturbations like those during the last decade recur every 50, 20, or 10 y during the next 100 y, we estimate a cumulative SLR from GIS dynamics by 2100 of approximately 10, 25, and 45 mm, respectively…Addition of the estimated 40 mm of SLR from changes in SMB [surface mass balance] by 2100 would result in a total SLR from Greenland of 85 mm by 2100.

Holy cow! Rahmstorf is telling us to be worried about 7000 mm of sea level rise due to the “complete meltdown of the Greenland ice sheet,” but Price et. al. say maybe 85 mm due to Greenland by 2100.

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I have paid Mr. O’Neill’s debt for him

August 5, 2010

I have been involved in a wager with Kevin O’Neill.  He claimed

“The North Pole has never been ice-free; not once in the history of the earth.

… and I can prove it. I’ll wager you $100 to be given to the other’s favorite charity.”

I took Mr. O’Neill up on this challenge and I chose Save the Children as my designated charity.  Mr. O’Neill chose Fisher House.  It is pretty obvious who won this challenge, as  the poll in my previous post underscores.  As I predicted, Mr. O’Neill has not paid his debt.  So,  I have paid Save the Children $100 myself to prevent them  from being stiffed by Mr. O’Neill.  Here is the email receipt (with my personal information blocked out)…

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The End of the line for Kevin O’Neill

July 28, 2010

When I accepted Mr. O’Neill’s challenge

The North Pole has never been ice-free; not once in the history of the earth.

… and I can prove it. I’ll wager you $100 to be given to the other’s favorite charity.

I said I would give hm “opportunity to address my criticisms” of his proof.  On July 26th I asked Mr. O’Neill the following…

You have submitted a few short comments after my refutation. Shall I take these comments as your response to my refutation? If so, then I am ready to proceed.

Mr. O’Neill responded with…

If for some reason you are waiting for me to tell you to proceed in your rebuttal – then please proceed.

Mr. O’Neill’s opportunity to respond to my refutation of his “proof” is now over.

Readers can consider the aggregate of his comments dated July 22nd to July 27th to be his address of my criticisms.

Conclusion

I will give my conclusion before I rebut Mr. O’Neill’s comments, since most people will not want to read the boring details. 

Mr. O’Neill has not addressed my refutation of his “proof.”  Instead he has engaged in a sophist and sophomoric game centered around his claimed inability to associate a scalar value with a point.  I suspect that he will never concede defeat and pay the required $100 to Save The Children.  I will wait a week in the weak hope that his conscience will get the better of him.   After that, I will pay Save The Children the $100 myself to prevent them from being stiffed by Mr. O’Neill.  I will post a receipt when that time comes.

Mr. O’Neill has posted two other comments that remain in my moderation queue.  One of them is a 1500 word treatise on my supposed moral, mental and/or character deficiencies.  The other is a whiny diatribe about how I treated him unfairly (boo hoo) by pointing out that a journal article he cited actually supported my view.  Both of these comments will receive special treatment and be released in their entirety at some future date.

In the mean time, I do not feel obligated to provide a forum for the unending dribble of sophistry coming from Mr. O’Neill.  New comments from Mr. O’Neill will go to my moderation queue, and unless they end up in my special treatment page for Mr. O’Neill, then in all likelihood will end up being deleted. Mr. O’Neill has overstayed his welcome

I may still have a little bit of  fun with his “proof” in some later posts though.

If you are interested in boring details, have a strong cup of coffee and read on…

Therefore I proceed

I ended my refutation of Mr. O’Neill’s “proof” with the following…

O’Neill needs to do all of the three following things: he must prove my paleontological & geological evidence is wrong; he must show that his “proof” does not lead to bizarre consequences; he must show that Li/Lt is “undefined” (as he claimed in his proof) as opposed to “indeterminate.”

Mr. O’Neill flippantly dismissed my paleontological & geological evidence with the statement “The geology/paleontology stuff is just irrelevant.”  Sorry Mr. O”Neill, your dismissal does not counter my refutation of your proof.  On that basis alone I have already won the wager.

However, I will play along with his clumsy sophistry for the moment

First sophistry (equivocation)

Mr. O’Neill couches his “proof” in the language of math and physics.  He defines the North Pole as a “point” in the mathematical sense.  He also defines two properties of this point when he says “Li is L’s ice covered area and Lt is L’s total area.”  He creates a metric for the ice covered fraction at L by taking the mathematical ratio of Li and Lt when he says “To satisfy the definition of ‘ice-free’ Li/Lt must be < .15.”  He later simply asserts that “for any point L the quotient for Li/Lt is always undefined.”

Why is “the quotient for Li/Lt is always undefined?”  He doesn’t explain this in his “proof.”  In some of his comments which he says can serve as a rebuttal to my refutation, he says that Lt is simply undefined because L has no area.  He explains that area is not a property of a point, and therefore Lt is undefined. 

But wait, didn’t he personally define Lt as an AREA when he said “Lt is L’s total AREA.”  So, he personally defines Lt as an area, uses it in his “proof,”  and then claims Lt is undefined to conclude the validity of his “proof.”  This is an extraordinary case of equivocation (Lt is defined as an AREA early in the “proof” and claimed  to be undefined later in the “proof.”).

The absurdity of his “proof” would be clear to all when the mask of  equivocation is lifted.  Suppose  his “proof” said “Li is L’s  ice-covered area and Lt is undefined”  and “To satisfy the definition of ‘ice-free’ Li/Lt must be < .15.”

O’Neill can’t just deliberately create what he feels is a bogus metric (Li/Lt with Lt undefined) and then claim that since his metric is bogus the thing being quantified must be undefined.

Second sophistry (non-sequitur)

O’Neill claims that since his metric (Li/Lt) cannot quantify the thing he wants to quantify (surface density of ice), then the thing he wants to quantify must be undefined.  Why?  Does the supposed failure of his metric prove that all other approaches will also fail?  This is a non-sequitur.

Third, and most important sophistry

 By calling the North Pole a “point” he thinks that he has removed all scalar properties associated that point.  That is, he deliberately tries to confuse the difference between the properties of a point with the properties associated with a point.

The only properties of a point are the n coordinates that define it in an n-dimensional space.  However, there are an infinite number of properties that can be associated with a point.  So, for example, while temperature is not a property of a point, it can be associated with a point.  When we speak of the temperature at a point, we are not talking about a property of the point, but rather a property associated with the point.  Similarly, and more importantly for this discussion, the surface density of ice is not a property of a point, it is a property associated with a point.  The usefulness of any coordinate system is zero without the ability to associate properties with points.

scalar is a quantity that can be described by a single number (either dimensionless, or in terms of some physical dimension).  A scalar field is an n-dimensional space with a scalar value associated with every point in a that space.  Temperature as a function of position and surface density of ice as a function of position are simple examples of scalar fields.  The concept of a scalar field is intuitive to most people, but is summed up nicely here

In mathematics and physics, a scalar field associates a single number (or scalar) to every point in space. Scalar fields are often used in physics, for instance to indicate the temperature distribution throughout space, or the air pressure.

Note to Mr. O’Neill:  air pressure is force per unit AREA.  By your reasoning, air pressure cannot be defined at a point.  But, in fact  it is always defined at a point.

Mr. O’Neill’s sophistry denies both the intuitive and mathematically rigorous concepts of a scalar field.  Why? Because he denies the possibility of associating a scalar property (such as surface density or temperature) with a point simply because that scalar property is not a property of the point.  He seems to see some clever trap or paradox in his own blind spot of understanding. 

Fourth sophistry

Mr. O’Neill has a choice: he can either say that his proof requires a mathematical foundation, or it does not.   O’Neill couches his “proof” in the language of mathematics, with definitions of variables (albeit equivocating definitions) and mathematical ratios.  Why blow smoke with all the math when he could have simply argued that “the concept of a surface density of ice at a point is simply undefined and therefore cannot have ever been less than 0.15. QED”   He couldn’t make this simple argument because he cannot back it up – the concept of the surface density of ice associated with a point is easily defined.

Mr. O’Neill’s attempts to brush aside the use of L’Hopital’s rule to resolve an indeterminacy of the surface density of ice at a point.   In a statement that stands as a monument to his mathematical ignorance,  Mr. O’Neill says…

Parenthetically, and irrelevant as far as I can see, I suspect that L’Hopital’s rule would not apply since the denominator is a constant zero – I suppose the numerator is as well. So, even if we accepted your 0/0 equation, would L’Hopital’s rule apply since we’re dealing with two constants and not a converging series?

While L’Hopital’s rule can be a useful tool to judge the convergence of a series, it is by no means used exclusively or even mostly for  that purpose.  It is typically used to find the value of f(x)/g(x) at a value of x that yields an indeterminate form (such as 0/0 or infinity divided by infinity).  Mr. O’Neill’s argument against the use of L’Hopital’s rule in this instance can best be summed up as the fallacy of  “invincible ignorance” (seriously, see the Philosophical Society).”  Mr. O’Neill, go back and take a first year calculus class, then re-read my refutation of  your “proof.”

Fifth sophistry (tu quoque)

I am afraid this gets to the heart of the matter for Mr. O’Neill.  As I mentioned in my refutation of his “proof,” Mr. O’Neill seeks to claim some sort of moral victory by saying that in order for me to win the wager I must retract some dishonest or misleading claim that the North Pole is a “point” in the mathematical sense.  Of course, I never made such a claim, Mr. O’Neill’s ramblings about my pictures of submarines at the North Pole notwithstanding.

When another commenter (Charlie A, July 19, 2010 at 2:17 pm) mockingly criticized Mr. O’Neill’s “proof” by saying “Perhaps, just perhaps, there is a logical fallacy in the proof” O’Neill responded (July 19, 2010 at 11:20 pm) with the following …

“There’s no logical fallacy. What there is is a lesson: It’s stupid to define the North Pole as s point when discussing ice-free conditions in the Arctic – otherwise we get this sort of nonsense.”

When I accepted Mr. O’Neill’s wager, I defined the term North Pole as

North Pole. This means the area at which the axis of rotation exits the current Northern Hemisphere. It is not the magnetic pole. The North Pole, for the purposes of this wager, does not change with a magnetic reversal. The North Pole is not required to include the entire Arctic Ocean or the entire Arctic Basin (features that have not even existed through the whole “history of the [E]arth”).

Mr. O’Neill twists himself into a logical pretzel trying to show that this definition implies I have defined the North Pole as a point in the mathematical sense.  He comments (2010/07/22 at 4:58 pm)

Someone said,

…the area at which the axis of rotation exits the current Northern Hemisphere ..

A line intersecting a sphere would be …. a point?

 Get it?  I said “area” in the colloquial sense, and Mr. O’Neill claims I said “point” in the mathematical sense.  Oh well, it doesn’t really make any difference.  Mr. O’Neill’s naive arguments about undefined values and the inapplicability of L’Hopital’s rule fail even if the North Pole is defined as a point the the mathematical sense.

In other words, Mr. O’Neill justifies making what he admits is a “stupid” argument because he claims I had already made the same argument (which, of course, I have not).  A pathetic case of tu quoque.

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Rahmstorf (2009): Off the mark again (part 1)

March 21, 2010

I was highly critical of Stefan Rahmstorf’s 2007 attempt to scare the world about sea level rise. He claimed that any temperature rise would result in an increase in the sea level rise rate that would take a millenium to dampen out. I pointed out at the time that this claim was contradicted by the very data that he used.

Rahmstorf”s original equation simple equated the sea level rise rate to the temperature above some equilibrium temperature.

where H is the sea level, dH/dt is the sea level rise rate (that is, the change in sea level per unit time, t), and T0 is some equilibrium temperature. According to this formula, when the temperature, T is constant, the sea level rise rate is constant. I pointed out instances where the instrumental temperature was nearly constant, but the sea level rise rate dropped, contradicting his model.

Now, Martin Vermeer and Rahmstorf (referred to as “VR2009” for the rest of this article) have given it another try. They have added another term, dT/dt which they say “corresponds to a sea-level response that can be regarded as ‘instantaneous.'”

where dT/dt is the change in temperature per unit time. They fit the GISS temperature data and tide gauge sea level data from Church and White (with a reservoir correction) to the equation to determine the best values for a, b and T0. For the sake of argument I will accept VR’s values (a = 0.56 +- 0.05 cm*a-1K-1, b = -4.9 +- 1.0 cm*K-1 and To = -0.41 +- 0.03 K).

Intuition might make you guess that the constant, b, would be a positive value, since it would seem that an increase in temperature would cause an increase in the sea level rise rate. But VR2009 found that the best fit to their data yielded a negative value for b (b = -4.9 +- 1.0 cm*K-1).

They proffer two possible explanations for this counter-intuitive result. The first is that when temperature rises “higher evaporation from the sea and subsequent storage of extra water on land, e.g., in form of soil moisture” results in an initial drop in sea level rise rate. They correctly discount this explanation by pointing out that “It is hard to see how the very large amount of water needed to be stored on land could remain inconspicuous.”

Their preferred explanation is as follows….

“Thus, the most plausible physical interpretation of our statistical fit is that the negative value of b results from a positive ocean mixed layer response combined with a lag of over a decade in the response of the ocean-cryosphere system. Several mechanisms could be envisaged for a delayed onset of sea-level rise after warming. For example, mass loss of ice sheets can be caused by warm water penetrating underneath ice shelves, triggering their collapse and subsequent speed-up of outlet glaciers banked up behind the ice shelf (21). We cannot explore causes of delay in more detail here, but note the statistical result is robust irrespective of its causes.”

description vs explanation

It is very important to understand that VR2009’s model (equation 2) is put forth as more than just a description of  sea leve rise for the last 120 years.  Rather it is an explanation for that sea level rise.  If this point is obvious to you, then please forgive me for belaboring it and skip to the next section.

But the difference between a formula that describes and a formula that explains is essential to understand,  For example, if you were to drop a rope on the ground in a random fashion you could come up with some kind of formula for the elevation of the rope at each point along the first half of its length.  Perhaps you would fit the elevation to an 10th order polynomial that mimics the pattern that the first half of the rope made.  But that formula would have no power to tell you the pattern of the second half of the rope.  Your formula would be a description of the pattern of the first half of the rope, but not an explanation.  Also, if you lifted your rope and dropped it in a new pattern, your formula would now be useless to predict the elevation of the first half of the rope again.

Now suppose you dropped your rope on the ground and noticed that the rope made contact with the ground along its entire length.  You could come up with a formula giving the elevation of the first half of the rope, Zr(x), as a function of the elevation of the ground, Zg(x).  Namely, Zr(x) = Zg(x).   This simple formula does more than describe the elevation of the rope – it explains it.  This simple formula has predictive power for the second half of the rope.  That is, given the elevation of the ground you can predict the elevation of any point on the second half of the rope.  This simple formula also lets you draw conclusions about what the elevation of the first half of the rope would have been if it had been dropped in a different pattern.

VR2009’s simple temperature rise scenario

If realistic data is applied to a model that is purported to explain a phenomenon, and the result is obviously unrealistic, then that model must be rejected.  In this section I will explain how VR2009 apply a realistic temperature scenario to their model, namely a linear increasing temperature, to explain the effect of the counter-intuitively negative value of the model parameter, b.  Their result is satisfying.  But in the next section I will apply another realistic temperature scenario to their model, and the result will be outrageously bogus.  This will force the rejection of their model and its predictive power for the 21st century.

VR2009’s preferred explanation for a negative b is that it is related to a physical phenomenon that results is a time lag between a temperature increase and an increase in sea level.   They consider a hypothetical case where the temperature, T, undergoes a steady linear rise starting at time t=0.   That is, T=ct, where c is a constant.   In this case, dT/dt = (d/dt)ct = c.  For the sake of simplicity, they assume that a temperature scale has been chosen such that T0=0.   Then…

Integrating gives…

The following image illustrates how equation 4 leads to an initial drop in sea level with an increasing temperature for their hypothetical linearly increasing temperature.

An example of how Vermeer and Rahmstorf's new model of sea level rise as a function of temperature leads to an initial drop in sea level with a linear temperature rise.

So, VR2009 have a model equation which counter-intuitively shows an initial drop in sea level rise with rising temperature. It is backed up by the just-so story about “warm water penetrating underneath ice shelves” of which they “cannot explore causes of delay in more detail here.”   Well, very nice.

An alternative temperature rise scenario

VR2009 used a simple linear increase in temperature to show it really makes sense that the constant, b, in their sea level rise rate model (equation 2) is negative. But  their model must work with any realistic temperature increase scenario.  So I propose at different type of temperature increase to test the saneness of their model.

Consider the case where…

Now, my hypothetical temperature is a bit more complicated than VR2009’s version (T=ct), but it is just as realistic, depending on the choice of C.  The image below shows and overlay of GISS temperature change from 1950 to 2000 (with a 15 year smoothing similar to that used by VR) , VR’s hypothetical temperature scenario and my hypothetical temperature scenario.  All three scenarios are examples of realistic temperature changes.  All three have been adusted to about the same starting time and temperaure for the sake of comparison.  For the VR2009 hypothetical, c=0.01 K-1a-1.  For the my hypothetical, C = 0.002 K, and a and b are the same as VR2009 derived for their model, namely, a = 0.56 cm*a-1 K-1, b = -4.9 cm*K-1.  For all three cases the temperature increase after fifty years is about half a degree.

What happens when we insert my hypothetical temperature (equation 5) into VR2009’s model (equation 2)?   Inserting equation 5 into equation 2 gives…

Carrying out the derivative on the right of equation 6 and collecting terms yields…

Surprise, Surprise!

The hypothetical temperature increase that I propose looks more like what we have seen in the last 50 years than the simple linear increasing temperature that VR2009 used for their illustrative purposes.    My hypothetical temperature scenario could be used to create a much more brutal “hockey stick” than anything proposed by Michael Mann by simply increasing the constant, C.  Yet in VR2009’s model it always results in a sea level rise of zero!   You could choose the constant C to yield a realistic 1 degree, or an unrealistic 20 degrees, or 100 degrees in 100 years – it doesn’t make any difference – VR2009’s model would still give a sea level rise of zero.  My simple test shows that VR2009’s model must be rejected.

This is not a trick of math.  VR2009 claim that their model (equation 2) should work with any temperature increase scenario.  In fact, they applied their model to 342 future temperature scenarios derived from “six emission scenarios, three carbon cycle feedback scenarios, and 19 climate models.”  But my hypothetical temperature increase scenario shows that their model describes sea level change in the 20th century, but does not explain it – despite their vague just-so story about time lags due to water penetrating under ice shelves, blah blah blah.  Consequently, it does not have predictive power for the 21st century.

But that doesn’t stop VR2009 from using this model to scare people about anthropogenic climate change induced sea level rise in the 21st century.

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Climate change doom data from the Southern Hemisphere

October 2, 2009

News Flash!!

Clear signs of climate doom in the Southern Hemisphere!!

Satellite data used to measure the seasonal growing and shrinking of sea ice area in the Southern Hemisphere make a stark realization clear: Five of the six most extreme yearly sea ice extents ever measured in the Southern Hemisphere have occurred in just the last 10 years.   As a planet and global community, we need to prepare for the worst.  The time to dither and argue is over – the time to act is now.

I call on the leading governments of the world, the United Nations, NGOs, environmental activists, and uber-informed stars of popular culture to meet in a central location (I suggest Emirates Palace in Abu Dhabi) to deal with this crisis.  They must develop an innovative plan to shepherd the other 6 billion people of the Earth to more environmentally sensitive life styles – before it’s too late. 

People must be taught to temper their greedy desire for luxuries such as electricity, safe shelter, food and clean water, and long life expectancies.  People need to learn how to overcome the archaic ambition of working to make a better life for their children.  Better yet, they should just stop having children.

If you do not understand the treacherous environmental precipice upon which we are poised, let the unalloyed data speak for itself.  Brace yourself – five of the six years with the greatest Southern Hemisphere sea ice extent have occurred in just the last decade!  If this historically unprecedented* trend continues, we are doomed.  See the graph below.

Southern hemisphere maximum sea ice area

Southern hemisphere maximum sea ice area. The data is real, but Tom Moriarty takes complete blame for all satirical content.

As you can see, the yearly maximum sea ice area in the Southern Hemisphere has been significantly larger in the last decade.   If we don’t act soon, the planet will become a barren ball of ice and snow.
 
 
*Since satellite data started being collected in 1979
 
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More on Thermohaline Circulation

June 16, 2009

In a previous post “The Thermohaline Circulation Only Stops for Extreme, Unrealistic Models,” I compared the amount of fresh water used in “hosing experiment” models to drastically reduce the thermohaline circulation (THC, or Meridional Overturning Circulation, MOC) to the amount of water flowing over Niagara Falls, or flowing from all rivers into the Arctic,  or coming off of Greenland due to melting ice.

The key number was one Sverdrup, or 1 million cubic meters of fresh water per second.  One Sverdrup of fresh water artificially dumped into the Labrador sea, for 100 years would have the feared effect.  But it turns out that one Sverdrup of fresh water is 350 times the amount of water flowing over Niagara falls, and about 300 times the amount of water from melting ice that flows off of Greenland.  It was seen that there is not plausible source for this amount of extra fresh water to be dumped into the arctic.

An interesting letter that appeared in Science a year ago gives a little more perspective,  So I have reproduced it in full here:

Freshwater Forcing: Will History Repeat Itself?

IN THEIR RESEARCH ARTICLE “REDUCED North Atlantic deep water coeval with the glacial Lake Agassiz freshwater outburst” (4 January, p. 60), H. F. Kleiven et al. present compelling evidence for an abrupt deep-ocean response to the release of freshwater from glacial Lake Agassiz into the northwest Atlantic about 8400 years ago. Such data are particularly important in evaluating the response in ocean models of the Atlantic Meridional Overturning Circulation (MOC) to freshwater forcing. For this event, the freshwater forcing was likely large but short; Clarke et al. (1) estimate that the flood had a freshwater flux of 4 to 9 Sv [Sverdrups] released in 0.5 years.

In this context, we are aware of no possible mechanism that might reproduce such a forcing in response to global warming, and all available model simulations, including those with estimates of maximum Greenland Ice Sheet (GIS) melting rates, indicate that it is very unlikely that the MOC will undergo an abrupt transition during the course of the 21st century (2). Multimodel ensemble averages under Special Report on Emissions Scenario (SRES) A1B suggest a best estimate of 25 to 30% reduction in the overall MOC strength (2). In one example, 14 coupled models simulated a 100-year 0.1-Sv freshwater perturbation to the northern North Atlantic Ocean—17 times the recently estimated melt rates from the GIS [Greenland Ice Sheet]—and the MOC weakened by a multimodel mean of 30% after 100 years; none of the models simulated a shutdown (3). Another model simulated greenhouse gas levels that increased to four times preindustrial values and then remained fixed; the resulting GIS displayed a peak melting rate of about 0.1 Sv, with little effect on the MOC (4). One model simulation uses the SRES  freshwater forcing as an upper-bound estimate of potential GIS melting. In this case, the MOC weakened but subsequently recovered its strength, indicating that GIS melting would not cause abrupt climate change in the 21st century (5). Accordingly, we urge caution in drawing comparisons of the abrupt change 8400 years ago to future scenarios involving, for example, the melting of the GIS and its relevance to human societies.

PETER U. CLARK1, THOMAS L. DELWORTH2, ANDREW J. WEAVER1
1Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
2Geophysical Fluid Dynamics Laboratory/NOAA, Princeton, NJ 08542, USA.
3School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8W 3P6, Canada.

References
1. G. K. C. Clarke, D. W. Leverington, J. T. Teller, A. S. Dyke, Quat. Sci. Rev. 23, 389 (2004).
2. G. A Meehl et al., in Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, S. Solomon et al., Eds. (Cambridge Univ. Press, New York, 2007), pp. 747–845.
3. R. J. Stouffer et al., J. Clim. 19, 1365 (2006).
4. J. K. Ridley, P. Huybrechts, J. M. Gregory, J. A. Lowe, J. Clim. 17, 3409 (2005).
5. J. H. Jungclaus, H. Haak, M. Esch, E. Roeckner, J. Marotzke, Geophys. Res. Lett. 33, 10.1029/2006GL026815 (2006).

So, the event that occurred 8400 years ago involved 4 to 9 Sverdrups of fresh water.  This is THOUSANDS of times greater than the flow of the Niagara Falls today.  It is THOUSANDS of times greater than the amount of fresh water flowing from melting Greenland ice today. It is multiples bigger than the entire fresh water budget into the Arctic.

Note that in my previous post I referred to hosing experiments that pumped up to one Sverdrup of fresh water into the oceans.   The authors of the above letter refer to hosing experiments that used only 0.1 Sverdrups – yet they still point out how gigantic this is compared to actual sources of fresh water in the Arctic today.

So, when Al Gore ominously implies that that the Greenland Ice Sheet [GIS] is going to melt down and dump enough fresh water into the Atlantic Ocean to shut down the Thermohaline Circulation, remember the works of Clarke, et.al., in the above letter: “we urge caution in drawing comparisons of the abrupt change 8400 years ago to future scenarios involving, for example, the melting of the GIS [Greenland Ice Sheet] and its relevance to human societies.”

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Impure thoughts about sea level rise

June 5, 2009

There has been some back and forth about the magnitude, consequences and proper response to sea level rise here, here, herehere and here. The alarmists would like to dismiss the evidence of man’s ability to cope. I have wondered why they think the history of free and motivated people pushing back against the ocean is irrelevant. But now this comment by Ed Darrell (from here) puts the alarmists’ mindset into clear focus.

Ed Darrel said:

Yeah, I saw the chart that said sea level is rising in Boston. It’s been rising as long as it’s been measured there, hasn’t it?

Not once did the harbormaster get together with the Brahmins of Boston to say, “We need to make Boston Neck thicker because of rising sea level.”

I didn’t say sea level didn’t rise. I said none of the landfills was done in response to rising sea level. The land was filled out for commercial needs, for commercial wants, and because when the weather created a bunch of new land, it could be used. Not once was any part of the harborscape built out to meet rising ocean levels.

So, to claim that Boston illustrates that the world can cope, is simply in error. Of course the world can cope in major harbors where there is plenty of commercial activity to combat a modest increase in ocean level.

What was your point?

So, apparently, Boston’s experience doesn’t count as evidence of man’s ability to push back against the ocean. Why? Because their actions were motivated by impure thoughts.

If I have properly deciphered Ed’s logic, then the following scenario does not show man’s ability to cope with the ocean:

Land in the Boston area is crowded and valuable. Engineers and the ‘Brahmins of Boston’ say “We could boost commerce by making Boston Neck thicker and recovering land from the sea.” Engineers design ways to push back the ocean and follow through on their plans.

But the following scenario would demonstrate man’s ability to cope with the ocean:

Land in the Boston area is crowded and valuable. Engineers and the ‘Brahmins of Boston’ say “We could fight against global warming by making Boston Neck thicker and recovering land from the sea.” Engineers design ways to push back the ocean and follow through on their plans.

Why would the second scenario illustrate man’s ability to cope with the ocean, but the first does not? In both cases they have the same problem and the same outcome. Here’s why: in the first scenario the engineers’ and brahmins’ motivations are impure, in the second scenario the engineers’ and brahmins’ motivations are pure.

Well, at least we have found some common ground. That is, we agree that the sea level has been rising near Boston, and we agree that Boston has been successful in pushing back the ocean.  But Ed can’t seem to understand that even if the ocean had not been rising near Boston for the last hundred years, their experience shows that they have the ability to cope if it started rising now.

Just Plain NutsVell, Mr. Darrell, I think vee have made some veal progress.  At our next session vee vill analyze your repression of impure thoughts concerning sea level vise.